This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book coincides with the global threat posed by the Coronavirus outbreak in Spring 2020. For professionals, fresh challenges have emerged in the last decade, often under the harsh gaze of public and political scrutiny. High expectations in a time of reduced resources (financial and human) have meant that professionals who work with children, families, and young people need to be multi-skilled, knowledgeable, and adaptable in the face of what has become almost constant change. A good knowledge of child development theory will lend confidence to students who are taking their initial steps in to the workplace.